df2.drop(df2.columns[[0, 1, 3]], axis=1, inplace=True)
C:/Users/����� �����������/Desktop/projects/youtube_log/filter.py:11: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead

df2 is now a slice of df1 and should trigger those pesky SettingWithCopyWarning's if we try to change things in df2. Let's take a look.

df2.drop('c')

No problems. How about:

df2.drop('c', inplace=True)

There it is:

The problem is that pandas tries to be efficient and tracks that df2 is pointing to the same data as df1. It is preserving that relationship. The warning is telling you that you shouldn't be trying to mess with the original dataframe via the slice.

Notice that when we look at df2, row 'c' has been dropped.

df2

And looking at df1 we see that row 'c' is still there.

df1

pandas made a copy of df2 then dropped row 'c'. This is potentially inconsistent with what our intent may have been considering we made df2 a slice of and pointing to same data as df1. So pandas is warning us.